The present invention relates to a one-pot enzyme curable drier package for a waterborne latex formulation.
The impetus to achieve low/zero VOC for water-borne coatings has necessitated the use of soft copolymers to attain film formation without volatile coalescent, at the expense of lower Tgs, which adversely impact hardness. Thus, crosslinking agents are typically used to impart hardness during the curing process. Ambient cure in high-performance coatings rely on reactive functional groups in polymer precursors to build three-dimensional cross-linked networks. Conventional curing reagents include oxidation catalysts (transition metal driers), free radical initiators and, chemical cross-linkers to achieve the desired result. Most traditional approaches require a two-pack system because it is often difficult to decouple the pot life from the curing time. Many of these conventional curing additives are disadvantaged by pre-cross-linking, reliance on two-component architecture, and toxicity as with metal driers such as cobalt naphthenate.
EP2589629 describes the use of oxidizing enzymes such as peroxidases and laccases as environmentally friendly substituents for ambient cure metal driers in alkyd systems. WO 01/28960 A1 describes enzymatic ambient crosslinking of synthetic urushi, which contains oxidizable phenolic groups. Nevertheless, ambient cure via enzymatic oxidation is often slow or ineffective in the absence additional additives, which may adversely impact the cure process.
It would therefore be an advance in the art to find a one-pot method for ambient cure of low VOC waterborne binder formulations.